Or you could like, I don't know, use actual infantry to protect your flank? You wouldn't expect combat engies to singlehandedly beat a flanking grenadier or volk squad right?
Or or, and stay with me on this one, it's a a big one, but you could try not getting flanked.
Pioneer have synergy with the MG42 and that is way the get the extra sight radius. And the where where buffed so that hey can fight flanking infatry at point blank. Else give them K98 CE style.
Being flanked means that one's opponents uses one infantry to draw fire and another to flank so not being flanked is not really an option.
And yea grenadiers are actually terrible at flanking and unless they use a rifle-grande the enemy HMG can reposition or simply retreat.